The 2024 Helena-Lamont, Oklahoma tornado was a violent, highly destructive, and extremely long-tracked EF4 tornado which left a path across much of northern Oklahoma late in the evening of Friday, May 31, 2024. Part of the 2024 Super Outbreak, the tornado touched down at 8:09 PM CDT in Woods County and tracked east-northeast, reaching EF4 strength to the southwest of Helena and remaining violent for over an hour and a half, leaving behind high-end EF4 damage in both Helena and Lamont, as well as surrounding rural areas. The tornado began to weaken to the east of Lamont, but remained on the ground for an additional 38 miles before dissipating between Kaw City and Shidler in Osage County at 10:47 PM.
The tornado was one of the longest-duration tornadoes ever recorded and the longest-tracked on record in the Great Plains states. Remaining on the ground for 2 hours and 51 minutes, the tornado left a path 131 miles long and 1.25 miles wide at its peak, although the tornado was at EF2 strength while at peak width, and less than 600 yards wide while at EF4 strength. Damage in Helena and Lamont was particularly intense, with at least one survey team assigning an EF5 rating. Poor construction quality of the obliterated buildings in both towns led to a final rating of high-end EF4, with estimated winds of 190 miles per hour. Over its path, the tornado was responsible for 12 deaths and 245 injuries.
The most notable aspect of the tornado was its extreme duration and path length. The tornado's path was by far the longest ever recorded in the Great Plains states, with the second-longest being the Canadian County, Oklahoma tornado on the same day, which left a path 102 miles in length. Notably, three other tornadoes on the same day also lasted for longer than two hours, and struck Piedmont, Oklahoma, South Bend, Texas, and Athens, Texas.